Weather or Lee Helm

New genny ??

Unless really worn out .... a sailmaker can often cut and resew a genny or main increasing or decreasing roach etc. as necessary.
Of course the easiest answer is to adjust sheets to change the sail balance .....

Yes it is true that heel alters undewater shape etc. and it is generally recognised that the the flatter a boat sails the better its performance ratio ... as the underwater surface is then balanced and optimum - those that wash windows with rails under are not necessarliy sailing faster but really getting an adrenaline rush !!
 
Re: New genny ??

[ QUOTE ]
Yes it is true that heel alters undewater shape etc. and it is generally recognised that the the flatter a boat sails the better its performance ratio ... as the underwater surface is then balanced and optimum - those that wash windows with rails under are not necessarliy sailing faster but really getting an adrenaline rush

[/ QUOTE ]

Not always true, many older designs go faster when heeled. Older racing rules favoured shorter waterline lengths without penalizing overhangs. The Liz 29 has a 4' increase in waterline length when the lee rail starts to go under, and sails at her fastest then.
 
Re: New genny ??

Liz 29 with a lwl 20'.
4" extra is almost 2% longer. Can you measure the speed increase as a result of that? Surely the increase in speed must be due to some other factor?
 
Re: New genny ??

I think your browser must be misreading the apostrophes.
4 feet, not 4 inches. I'm sure there's a rude joke in there somewhere.

It's difficult to quantify the speed increase due to WL increase compared with wind speed increase, but I have had her up to 9-10 knots in flat water. Once. Close hauled with full sail in a sudden gust of f5-6, approaching the entrance to N. Fambridge marina. Singlehanded. A real sphincter testing moment.

Other 9kt+ moments have been in open water, and I accept that the towed log can be over optimistic in these cases, but in an F5, 6-7kts is not unusual.
 
Heeling ...

I do not disgree that the boat sails faster ......... I said that performance ratio suffers and that some boats washing windows are not faster.

I agree that some boats designs incorporate a factor to allow the boat heeled - but it still affects the ratio of sail effort to hull speed vs wind speed.

Boats are designed primarily to have equal wetted surface both sides of keel ... later race boats have tried to balance this out to keep wetted surface reasonably constant till extreme heel ...... but it is easy to imagine that this is always a compromise.

My boat in tallinn (ex boat now sadly ) - regularly pulled away from competitors when she is less heeled and sails set for optimum rather than thrash the arse out of them and get wet ! And she was not so different from the Liz 29 ... maybe quicker etc. but still an older more trad design etc. like liz.

/forums/images/graemlins/cool.gif
 
Re: New genny ??

I am totally at fault. They don't seem to make apostrophes as big as they used to.
Yes that would be a 20% increase in lwl. Still only theoretically about 0.6 knots, but measurable.

(wait for all the "can't calculate without knowing wetted area etc" comments)
 
You must log in or register to reply here.

Share this page

Top